1. Field of the Invention
The present invention relates generally to spacecraft antenna reflectors and, more particularly, to a hub mounted bending beam for shape adjustment of springback reflectors.
2. Description of the Related Art
Spacecraft antenna reflectors are typically constructed as concave disks. Electrical specifications for the reflector dictate disk dimensions, specifically diameter and cross-sectional curvature. Spacecraft payload weight limits often constrain the reflector thickness to a level that renders the reflector vulnerable to dynamic forces associated with the spacecraft launch. Atmosphere drag and launch booster vibration may be particularly damaging to the reflector if the reflector is mounted in a typical operational configuration (i.e., on support collars on the external surface of the spacecraft) during launch. It is therefore desirable to store the reflectors in a confining envelope designed to protect the reflectors from launch stress.
The shape of the confining envelope requires temporary modification of the intrinsic antenna reflector shape to fit inside the envelope during launch. After launch, the reflectors are released from the envelope and returned to the original shape thereof on deployment. One approach for temporarily modifying the reflector shape is disclosed in Robinson, Simplified Spacecraft Antenna Reflector for Stowage and Confined Envelopes, U.S. Pat. No. 5,574,472, which is expressly incorporated in its entirety by reference herein. In the Robinson patent, a concave reflector fabricated from a flexible, semi-rigid material is deformed by application of a uniform force at diametrically opposed points at the periphery of the reflector. These forces cause the reflector to assume a shape similar to a taco shell which is maintained while the reflector is stowed. Upon deployment, the forces are removed from the reflector and the reflector reassumes its concave shape.
Deforming and stowing the reflector in this manner can cause distortion of the reflector from its desired shape. Additionally, other factors can cause distortion of the reflector from its desired shape. These factors include the predisposition of the reflector to fold on its own after fabrication, and thermal effects on and moisture absorption by the material from which the reflector is fabricated. The distorted shape ultimately results in the degradation of the performance of the reflector after the reflector is deployed and in use by the satellite.
Therefore, there is a need for an improved apparatus and method for adjusting the shape of springback reflectors to correct distortions caused by storage of the reflectors, fabrication of the reflectors, thermal effects and moisture absorption by the reflector material.